1. Field of the Invention
The present invention relates to an electron beam lens of a micro-column electron beam apparatus used for an electron beam exposure process of a semiconductor manufacturing process and a method of fabricating the same.
2. Description of the Related Art
A micro-column electron beam apparatus is used for patterning a semiconductor device as designed by focusing an electron beam generated at a cathode onto a resist film coated on a semiconductor wafer or a mask. The micro-column electron beam apparatus includes a deflector and electron beam lenses such as a source lens and a focus lens.
A deflector disposed between the electron beam lenses of the micro-column electron beam apparatus electrically controls the direction of the electron beam generated at the cathode such that the electron beam is projected onto the wafer or mask according to design data received from a pattern generator.
An electron beam lens of the micro-column electron beam apparatus includes a plurality of sequentially stacked thin conductive films in which a base isolation substrate is disposed between the conductive films. A hole through which the electron beam passes is formed at a center of each of the conductive thin films. Each of the base isolation substrates that acts as an insulator to maintain a uniform distance between adjacent conductive thin films, has a hollowed space which is larger than the hole through which the electron beam passes. The electron beam passing through is focused or dispersed by an electric potential applied to the conductive thin films as it passes through the holes in the central portion of the conductive thin films.
In a conventional method of manufacturing the electron beam lens, the conductive thin films are manufactured separately with a thickness of several μm and attached to both sides of an individual substrate such as pyrex glass using an anodic bonding method. The conductive thin film is a conductive silicon thin film including a boron doped layer on a wafer or a thin metal sheet of chrome, wherein the conductive silicon thin film is formed by forming a boron doped layer on a silicon wafer that has a thickness of 0.2˜1 mm, forming a membrane on by etching backside of the silicon wafer, and then forming a hole by reactive ion etching process that leaves the boron doped layer on the wafer.
In order to manufacture an electron beam lens capable of focusing or dispersing the electron beams as intended, the conductive thin films must be parallel and the holes must be positioned accurately with respect to the central portion during a stacking process of the conductive thin films. However, in the prior art, parallel arrangement of the conductive thin films and the in-line alignment of the holes is very difficult because each conductive film is separately manufactured and stacked. Particularly, a required bonding technique is very complicated and troublesome. Therefore, the conventional method of manufacturing an electron beam lens has poor reproducibility and produces lenses with a weak mechanical structure.